The gut microbiome has a significant impact on host health, especially at the metabolic level. Dietary compounds arriving at the colon have a large influence on the composition of the gut microbiome. High fiber diets have been associated to health benefits that are mediated in great part by short chain fatty acids (SCFA). Gut microbial interactions are relevant for the utilization of complex carbohydrates in the gut microbiome. In this work we characterized the utilization of two dietary polysaccharides by combinations of representative adult gut microbes, and the impact of their activities on a cellular inflammation model. Paired combinations of Bifidobacterium adolescentis, Bacteroides dorei, Lactobacillus plantarum, Escherichia coli and Clostridium symbiosum were grown in inulin or xylan as carbon source. Their relative abundance, substrate consumption and major SCFAs produced were determined. Higher cell growth was observed during inulin consumption, and B. adolescentis and L. plantarum were dominant in co-cultures. The co-culture of B. dorei and C. symbiosum was dominant in xylan. In several cases the combined bacterial growth was lower in co-cultures than monocultures, with a few exceptions of synergistic growth between microorganisms. Inulin fermentation resulted in larger acetate and lactate concentrations, and several combinations grown in xylan containing C. symbiosum were characterized by high amounts of butyrate. These microbial consortia were scaled to batch bioreactor fermentations reaching high cell densities and similar profiles to co-culture experiments. Interestingly, a microbial combination producing high amounts of butyrate was able to reduce IL-8 expression in HT-29 cells co-incubated with TNFα. In summary, this work shows that microbial interactions during the utilization of dietary polysaccharides are complex and substrate dependent. Moreover, certain combinations deploy potent anti-inflammatory effects, which are independent of individual microbial growth, and could be mediated in part by higher butyrate production.

肠道微生物组对宿主健康有重要影响，尤其是在代谢水平上。到达结肠的饮食化合物对肠道微生物组的组成有很大影响。高纤维饮食与健康益处有关，这在很大程度上是由短链脂肪酸（SCFA）介导的。肠道微生物相互作用与肠道微生物组中复杂碳水化合物的利用有关。在这项工作中，我们通过代表性的成年肠道微生物的组合来表征两种饮食多糖的利用，以及它们的活性对细胞炎症模型的影响。青春双歧杆菌，双歧杆菌，植物乳杆菌，大肠杆菌的配对组合菊苣和共生梭菌在菊粉或木聚糖中生长为碳源。确定了它们的相对丰度，底物消耗量和产生的主要SCFA。在摄入菊粉的过程中观察到更高的细胞生长，并且青春双歧杆菌和植物乳杆菌在共培养中占主导地位。B. dorei和C. symbiosum的共培养在木聚糖中占主导地位。在某些情况下，联合培养中细菌的合并生长低于单培养，但微生物之间的协同生长除外。菊粉发酵导致较高的乙酸盐和乳酸浓度，并且几种组合在含有共生梭菌的木聚糖中生长其特点是丁酸含量高。将这些微生物联盟按比例放大以达到高细胞密度和与共培养实验相似的特性，分批进行生物反应器发酵。有趣的是，产生大量丁酸的微生物组合能够降低与TNFα共孵育的HT-29细胞中IL-8的表达。总而言之，这项工作表明在饮食多糖利用过程中的微生物相互作用是复杂的且依赖于底物。此外，某些组合具有有效的抗炎作用，而这些作用与单个微生物的生长无关，并且可以部分由较高的丁酸酯产量介导。